He became the face of post-September 11 illness after his death in early 2006, galvanizing lawmakers and health care advocates to lobby for research and treatment for thousands who breathed the debris-filled air at ground zero.

James Zadroga, the 34-year-old retired police detective who died of respiratory failure after working hundreds of hours at the World Trade Center site, was often cited by those advocates as a "sentinel case" -- the first health-related casualty linked to ground zero, suggesting there would be more to follow.

The city's medical examiner stunned that community this week with a letter declaring that Zadroga's death had nothing to do with the toxic air he breathed while working at ground zero.

Rejecting another medical examiner's autopsy, New York City Chief Medical Examiner Charles Hirsch said in a letter to Zadroga's family that his death was not caused by exposure to trade center dust.

"It is our unequivocal opinion, with certainty beyond doubt, that the foreign material in your son's lungs did not get there as the result of inhaling dust at the World Trade Center or elsewhere," said the letter to Zadroga's father. It was signed by Hirsch and another medical examiner, Michele Slone. The letter was obtained Thursday by The Associated Press.

The article also notes that "[t]he city is defending itself in a lawsuit filed by thousands of workers who say they were not properly protected from the dust."